/*-------------------------------------------------------------------------
 *
 * arrayutils.c--
 *    This file contains some support routines required for array functions.
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    $Header: /usr/local/cvsroot/postgres95/src/backend/utils/adt/arrayutils.c,v 1.3 1996/11/10 03:03:03 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */

#define WEAK_C_OPTIMIZER

#include "postgres.h"

#include "utils/array.h"

int
GetOffset(int n, int dim[], int lb[], int indx[])
{                                              
    int i, scale, offset;                                     
    for (i = n-1, scale = 1, offset = 0; i >= 0; scale*=dim[i--]) 
        offset += (indx[i] - lb[i])*scale;
    return offset ;
}

int
getNitems(int n, int a[])
{    
    int i, ret;      
    for (i = 0, ret = 1; i < n; ret *= a[i++]);   
    if (n == 0) ret = 0;     
    return ret;
}

int
compute_size(int st[], int endp[], int n, int base)
{
    int i, ret;
    for (i = 0, ret = base; i < n; i++)
        ret *= (endp[i] - st[i] + 1);
    return ret;
}

void
mda_get_offset_values(int n, int dist[], int PC[], int span[])
{                                                                     
    int i, j;                                                         
    for (j = n-2, dist[n-1]=0; j  >= 0; j--)                         
	for (i = j+1, dist[j] = PC[j]-1; i < n;                             
	     dist[j] -= (span[i] - 1)*PC[i], i++);                         
}                                                                 

void
mda_get_range(int n, int span[], int st[], int endp[])
{                                                                     
    int i;                                                         
    for (i= 0; i < n; i++)                             
        span[i] = endp[i] - st[i] + 1;                 
} 

void
mda_get_prod(int n, int range[], int P[])
{                                                                     
    int i;                                                         
    for (i= n-2, P[n-1] = 1; i >= 0; i--)             
        P[i] = P[i+1] * range[i + 1];                 
} 

int
tuple2linear(int n, int tup[], int scale[])
{
    int i, lin;
    for (i= lin = 0; i < n; i++)
        lin += tup[i]*scale[i];
    return lin;
} 

void
array2chunk_coord(int n, int C[], int a_coord[], int c_coord[])
{
    int i;
    for (i= 0; i < n; i++)
	c_coord[i] = a_coord[i]/C[i];
}

/*-----------------------------------------------------------------------------
  generates the tuple that is lexicographically one greater than the current
  n-tuple in "curr", with the restriction that the i-th element of "curr" is
  less than the i-th element of "span".
  RETURNS   0   if no next tuple exists
  1   otherwise
  -----------------------------------------------------------------------------*/
int
next_tuple(int n, int curr[], int span[])
{
    int i;
    
    if (!n) return(-1);
    curr[n-1] = (curr[n-1]+1)%span[n-1];
    for (i = n-1; i*(!curr[i]); i--)
        curr[i-1] = (curr[i-1]+1)%span[i-1];
    
    if (i) 
        return(i);
    if (curr[0]) 
        return(0);
    return(-1);
}

